Studies will evaluate the importance of the immune response in lower vertebrates as a growth regulating mechanism. The speed and degree of forelimb regeneration are correlated with the immunomodulated status of the animal. The research attempts to answer questions relative to the ontogeny of the mammalian immune response to tumor tissue. BIBLIOGRAPHIC REFERENCE: Andrews, E.J.: Immunostimulation as a modulator of regeneration and growth. Amer. Zool. 16: 260, 1976 (abstract).